Method of making a polyurethane foam having improved flame retardance and aged k-factors

ABSTRACT

There is now provided a method for making a polyisocyanate based rigid closed cell foam by reacting an organic isocyanate and a polyol composition containing a polyol having polyester linkages and a number average molecular weight of 400 or more, and at least about 8 php of a silicone-containing surfactant polymer, in the presence of an aliphatic or cycloaliphatic C4-C7 hydrocarbon blowing agent. Either mixed into the polyol composition at the time of foaming, mixed into an isocyanate, or both, is an aliphatic or cycloaliphatic C4-C7 hydrocarbon.

FIELD OF THE INVENTION

The present invention relates to a method for making rigid closed cellpolyisocyanate based foams. In particular, the present invention relatesto a method for making a foam by using a polyol composition whichcontains a polyol having polyester linkages and at least about 8 php ofa silicone-containing surfactant polymer, along with an aliphatic orcycloaliphatic C₄ -C₇ hydrocarbon blowing agent mixed into the polyolcomposition and/or into the isocyanate, for the purpose of improving theflame retardance and aged k-factor of foams made thereby.

BACKGROUND OF THE INVENTION

Recently, C₄ -C₇ hydrocarbon blowing agents have gained increasingimportance as zero ozone depletion potential alternative blowing agentsfor polyurethane foams. One problem associated with hydrocarbons per seis their flammability and their relatively poor insulation factorscompared to CFC-11. Efforts have been underway to make hydrocarbon blownpolyurethane foams having good k-factors and as flame resistant aspossible, without sacrificing the mechanical properties of the foam. Itwould be desirable to improve the flammability of a hydrocarbon blownfoam using inexpensive and currently widely commercially availableingredients. It would also be desirable that such ingredient(s) does notrequire addition of further isocyanate to retain the same isocyanateindex, thereby further adding to the cost of the foam. Furthermore, suchan ingredient should not degrade the physical properties of the foam,such as the k-factor, compressive strength, and friability.

SUMMARY OF THE INVENTION

There is now provided a polyol composition containing a polyol havingpolyester linkages and a number average molecular weight of 400 or more,and at least about 8 php of a silicone-containing surfactant polymer.Either mixed into the polyol composition at the time of foaming, mixedinto an isocyanate, or both, is an aliphatic or cycloaliphatic C₄ -C₇hydrocarbon. There is also provided a polyisocyanate based closed cellrigid foam and method for making such by reacting an organic isocyanateand the polyol composition in the presence of an aliphatic orcycloaliphatic C₄ -C₇ hydrocarbon blowing agent.

The high levels of silicone-containing surfactant surprisingly led notonly to an improvement in flammability resistance as measured by theButler Chimney test, but also improved, rather than retained at statusquo, the other mechanical properties of the foam, such as the agedk-factors and thermal insulation loss over a 30 day period, thecompression strength and friability. No significant improvement in anyof these properties was noticed when the amount of surfactant polymerwas used a the conventional levels of about 2 php or above, until about8 php of the silicone surfactant polymer was added. Furthermore, thesilicone-containing polymers are widely commercially available, and mayof them are nonreactive with the isocyanate so no additional costs areadded to the foam through additional isocyanate use.

DETAILED DESCRIPTION OF THE INVENTION

As the first ingredient in the polyol composition, there is provided ana) polyol having polyester linkages. Preferably, the total amount ofpolyols in the polyol composition having number average molecularweights of 400 or more have an average functionality of 1.8 to 8, morepreferably 3 to 6, and an average hydroxyl number of 150 to 850, morepreferably 350 to 800. Polyols having hydroxyl numbers andfunctionalities outside this range may be used so long as the averagehydroxyl number for the total amount of polyols used fall within theaforementioned ranges.

Other types of polyols may be used in combination with the polyol havingpolyester linkages. Examples of polyols are thioether polyols, polyesteramides and polyacetals containing hydroxyl groups, aliphaticpolycarbonates containing hydroxyl groups, amine terminatedpolyoxyalkylene polyethers, polyoxyalkylene polyether polyols, and graftdispersion polyols. Mixtures of at least two of these polyols can beused so long as a polyol having polyester linkages is present in thepolyol composition in the aforesaid range.

The terms "polyol having polyester linkages" and "polyester polyol" asused in this specification and claims includes any minor amounts ofunreacted polyol remaining after the preparation of the polyester polyoland/or unesterified low molecular weight polyols (e.g., glycol) addedafter the preparation of the polyester polyol. The polyester polyol caninclude up to about 40 weight percent free glycol.

Polyols having polyester linkages broadly include any polyol having twoor more ester linkages in the compound, such as the conventionalpolyester polyols and the polyester-polyether polyols.

The polyester polyols advantageously have an average functionality ofabout 1.8 to 8, preferably about 1.8 to 5, and more preferably about 2to 3. The commercial polyester polyols used generally have averagehydroxyl numbers within a range of about 15 to 750, preferably about 30to 550, and more preferably about 150 to 500 (taking into account thefree glycols that may be present), and their free glycol contentgenerally is from about 0 to 40 weight percent, and usually from 2 to 15weight percent, of the total polyester polyol component. In calculatingthe average functionality and hydroxyl number of the total amount ofpolyols used in the polyol composition, the presence of the free glycolsis not taken into account because the glycols have number averagemolecular weights of less than 400.

Suitable polyester polyols can be produced, for example, from organicdicarboxylic acids with 2 to 12 carbons, preferably aliphaticdicarboxylic acids with 4 to 6 carbons and aromatic bound dicarboxylicacids, and multivalent alcohols, preferably diols, with 2 to 12 carbons,preferably 2 to 6 carbons. Examples of dicarboxylic acids includesuccinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid,sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid,phthalic acid, isophthalic acid, and terephthalic acid. The dicarboxylicacids can be used individually or in mixtures. Instead of the freedicarboxylic acids, the corresponding dicarboxylic acid derivatives mayalso be used such as dicarboxylic acid mono- or di- esters of alcoholswith 1 to 4 carbons, or dicarboxylic acid anhydrides. Dicarboxylic acidmixtures of succinic acid, glutaric acid and adipic acid in quantityratios of 20-35:35-50:20-32 parts by weight are preferred, as well asterephthalic acid and isophthalic acid and their 1-4 carbon esterderivatives. Examples of divalent and multivalent alcohols, especiallydiols, include ethanediol, diethylene glycol, 1,2- and 1,3-propanediol,dipropyleneglycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,1,10-decanediol,glycerine and trimethylolpropanes, tripropylene glycol,tetraethylene glycol, tetrapropylene glycol, tetramethylene glycol,1,4-cyclohexane-dimethanol, ethanediol, diethylene glycol,1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, or mixtures of at leasttwo of these diols are preferred, especially mixtures of 1,4-butanediol,1,5-pentanediol, and 1,6-hexanediol. Furthermore, polyester polyols oflactones, e.g., ε-caprolactone or hydroxycarboxylic acids, e.g.,ω-hydroxycaproic acid, may also be used.

The polyester polyols can be produced by polycondensation of organicpolycarboxylic acids, e.g., aromatic or aliphatic polycarboxylic acidsand/or derivatives thereof and multivalent alcohols in the absence ofcatalysts or preferably in the presence of esterification catalysts,generally in an atmosphere of inert gases, e.g., nitrogen, carbondioxide, helium, argon, etc., in the melt at temperatures of 150° to250° C., preferably 180° to 220° C., optionally under reduced pressure,up to the desired acid value which is preferably less than 10,especially less than 2. In a preferred embodiment, the esterificationmixture is subjected to polycondensation at the temperatures mentionedabove up to an acid value of 80 to 30, preferably 40 to 30, under normalpressure, and then under a pressure of less than 500 mbar, preferably 50to 150 mbar. The reaction can be carried out as a batch process orcontinuously. When present, excess glycol can be distilled from thereaction mixture during and/or after the reaction, such as in thepreparation of low free glycol-containing polyester polyols usable inthe present invention. Examples of suitable esterification catalystsinclude iron, cadmium, cobalt, lead, zinc, antimony, magnesium, titaniumand tin catalysts in the form of metals, metal oxides or metal salts.However, the polycondensation may also be preformed in liquid phase inthe presence of diluents and/or chlorobenzene for aziotropicdistillation of the water of condensation.

To produce the polyester polyols, the organic polycarboxylic acidsand/or derivatives thereof and multivalent alcohols are preferablypolycondensed in a mole ratio of 1:1-1.8, more preferably 1:1.05-1.2.

After transesterification or esterification, the reaction product can bereacted with an alkylene oxide to form a polyester-polyether polyolmixture. This reaction desirably is catalyzed. The temperature of thisprocess should be from about 80° to 170° C., and the pressure shouldgenerally range from about 1 to 40 atmospheres. While the aromaticpolyester polyols can be prepared from substantially pure reactantmaterials, more complex ingredients are advantageously used, such as theside stream, waste or scrap residues from the manufacture of phthalicacid, terephthalic acid, dimethyl terephthalate, polyethyleneterephthalate, and the like. Particularly suitable compositionscontaining phthalic acid residues for use in the invention are (a)ester-containing byproducts from the manufacture of dimethylterephthalate, (b) scrap polyalkylene terephthalates, (c) phthalicanhydride, (d) residues from the manufacture of phthalic acid orphthalic anhydride, (e) terephthalic acid, (f) residues from themanufacture of terephthalic acid, (g) isophthalic acid, (h) trimelliticanhydride, and (i) combinations thereof. These compositions may beconverted by reaction with the polyols of the invention to polyesterpolyols through conventional transesterification or esterificationprocedures.

Polyester polyols whose acid component advantageously comprises at leastabout 30 percent by weight of phthalic acid residues are useful. Byphthalic acid residue is meant the group: ##STR1##

A preferred polycarboxylic acid component for use in the preparation ofthe aromatic polyester polyols is phthalic anhydride. This component canbe replaced by phthalic acid or a phthalic anhydride bottomscomposition, a phthalic anhydride crude composition, or a phthalicanhydride light ends composition, as such compositions are defined inU.S. Pat. No. 4,529,744.

Other preferred materials containing phthalic acid residues arepolyalkylene terephthalates, especially polyethylene terephthalate(PET), residues or scraps.

Still other preferred residues are DMT process residues, which are wasteor scrap residues from the manufacture of dimethyl terephthalate (DMT).The term "DMT process residue" refers to the purged residue which isobtained during the manufacture of DMT in which p-xylene is convertedthrough oxidation and esterification with methanol to the desiredproduct in a reaction mixture along with a complex mixture ofbyproducts. The desired DMT and the volatile methyl p-toluate byproductare removed from the reaction mixture by distillation leaving a residue.The DMT and methyl p-toluate are separated, the DMT is recovered andmethyl p-toluate is recycled for oxidation. The residue which remainscan be directly purged from the process or a portion of the residue canbe recycled for oxidation and the remainder diverted from the processor, if desired, the residue can be processed further as, for example, bydistillation, heat treatment and/or methanolysis to recover usefulconstituents which might otherwise be lost, prior to purging the residuefrom the system. The residue which is finally purged from the process,either with or without additional processing, is herein called DMTprocess residue.

These DMT process residues may contain DMT, substituted benzenes,polycarbomethoxy diphenyls, benzyl esters of the toluate family,dicarbomethoxy fluorenone, carbomethoxy benzocoumarins and carbomethoxypolyphenols. Cape Industries, Inc. sells DMT process residues under thetrademark Terate® 101. DMT process residues having a differentcomposition but still containing the aromatic esters and acids are alsosold by DuPont and others. The DMT process residues to betransesterified in accordance with the present invention preferably havea functionality at least slightly greater than 2. Such suitable residuesinclude those disclosed in U.S. Pat. Nos. 3,647,759; 4,411,949;4,714,717; and 4,897,429; the disclosures of which with respect to theresidues are hereby incorporated by reference.

Examples of suitable polyester polyols are those derived from PET scrapand available under the designation Chardol 170, 336A, 560, 570, 571 and572 from Chardonol and Freol 30-2150 from Freeman Chemical. Examples ofsuitable DMT derived polyester polyols are Terate® 202, 203, 204, 254,2541, and 254A polyols, which are available from Cape Industries.Phthalic anhydride derived polyester polyols are commercially availableunder the designation Pluracol® polyol 9118 from BASF Corporation, andStepanol PS-2002, PS-2402, PS-2502A, PS-2502, PS-2522, PS-2852, PS-2852E, PS-2552, and PS-3152 from Stepan Company.

Polyoxyalkylene polyether polyols, which can be obtained by knownmethods, can be mixed with the polyol having polyester linkages. Forexample, polyether polyols can be produced by anionic polymerizationwith alkali hydroxides such as sodium hydroxide or potassium hydroxideor alkali alcoholates, such as sodium methylate, sodium ethylate, orpotassium ethylate or potassium isopropylate as catalysts and with theaddition of at least one initiator molecule containing 2 to 8,preferably 3 to 8, reactive hydrogens or by cationic polymerization withLewis acids such as antimony pentachloride, boron trifluoride etherate,etc., or bleaching earth as catalysts from one or more alkylene oxideswith 2 to 4 carbons in the alkylene radical. Any suitable alkylene oxidemay be used such as 1,3-propylene oxide, 1,2- and 2,3-butylene oxide,amylene oxides, styrene oxide, and preferably ethylene oxide and1,2-propylene oxide and mixtures of these oxides. The polyalkylenepolyether polyols may be prepared from other starting materials such astetrahydrofuran and alkylene oxide-tetrahydrofuran mixtures;epihalohydrins such as epichlorohydrin; as well as aralkylene oxidessuch as styrene oxide. The polyalkylene polyether polyols may haveeither primary or secondary hydroxyl groups.

Included among the polyether polyols are polyoxyethylene glycol,polyoxypropylene glycol,polyoxybutylene glycol, polytetramethyleneglycol, block copolymers, for example, combinations of polyoxypropyleneand polyoxyethylene glycols, poly-1,2-oxybutylene and polyoxyethyleneglycols, poly-1,4-tetramethylene and polyoxyethylene glycols, andcopolymer glycols prepared from blends or sequential addition of two ormore alkylene oxides. The polyalkylene polyether polyols may be preparedby any known process such as, for example, the process disclosed byWurtz in 1859 and Encyclopedia of Chemical Technology, Vol. 7, pp.257-262, published by Interscience Publishers, Inc. (1951) or in U.S.Pat. No. 1,922,459.

Polyethers which are preferred include the alkylene oxide additionproducts of polyhydric alcohols such as ethylene glycol, propyleneglycol, dipropylene glycol, trimethylene glycol, 1,2-butanediol,1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, hydroquinone,resorcinol glycerol, glycerine, 1,1,1-trimethylol-propane,1,1,1-trimethylolethane, pentaerythritol, 1,2,6-hexanetriol, α-methylglucoside, sucrose, and sorbitol. Also included within the term"polyhydric alcohol" are compounds derived from phenol such as2,2-bis(4-hydroxyphenyl)-propane, commonly known as Bisphenol A.

Suitable organic amine starting materials include aliphatic andcycloaliphatic amines and mixtures thereof, having at least one primaryamino group, preferably two or more primary amino groups, and mostpreferable are the diamines. Specific non-limiting examples of aliphaticamines include monoamines having 1 to 12, preferably 1 to 6 carbonatoms, such as methylamine, ethylamine, butylamine, hexylamine,octylamine, decylamine and dodecylamine; aliphatic diamines such as1,2-diaminoethane, propylene diamine, 1,4-diaminobutane,1,6-diaminohexane, 2,2-dimethyl-,3-propanediamine,2-methyl-1,5-pentadiamine, 2,5-dimethyl-2,5-hexanediamine, and4-aminomethyloctane-1,8-diamine, and amino acid-based polyamines such aslysine methyl ester, lysine aminoethyl ester and cystine dimethyl ester;cycloaliphatic monoamines of 5 to 12, preferably of 5 to 8, carbon atomsin the cycloalkyl radical, such as cyclohexylamine and cyclo-octylamineand preferably cycloaliphatic diamines of 6 to 13 carbon atoms, such ascyclohexylenediamine, 4,4'-, 4,2'-, and 2,2'-diaminocyclohexylmethaneand mixtures thereof; aromatic monoamines of 6 to 18 carbon atoms, suchas aniline, benzylamine, toluidine and naphthylamine and preferablyaromatic diamines of 6 to 15 carbon atoms, such as phenylenediamine,naphthylenediamine, fluorenediamine, diphenyldiamine, anthracenediamine,and preferably 2,4- and 2,6-toluenediamine and 4,4'-, 2,4'-, and2,2'-diaminodiphenylmethane, and aromatic polyamines such as2,4,6-triaminotoluene, mixtures of polyphenyl-polymethylene-polyamines,and mixtures of diaminidiphenylmethanes andpolyphenyl-polymethylene-polyamines. Preferred are ethylenediamine,propylenediamine, decanediamine, 4,4'-diaminophenylmethane,4,4'-diaminocyclohexylmethane, and toluenediamine.

Suitable initiator molecules also include alkanolamines such asethanolamine, diethanolamine, N-methyl- and N-ethylethanolamine,N-methyl- and N-ethyldiethanolamine and triethanolamine plus ammonia.

Suitable polyhydric polythioethers which may be condensed with alkyleneoxides include the condensation product of thiodiglycol or the reactionproduct of a dicarboxylic acid such as is disclosed above for thepreparation of the polyester polyols with any other suitable thioetherglycol.

The polyester polyol may also be a polyester amide such as is obtainedby including some amine or amino alcohol in the reactants for thepreparation of the polyesters. Thus, polyester amides may be obtained bycondensing an amino alcohol such as ethanolamine with the polycarboxylicacids set forth above or they may be made using the same components thatmake up the polyester polyol with only a portion of the components beinga diamine such as ethylene diamine.

Polyhydroxyl-containing phosphorus compounds which may be used includethose compounds disclosed in U.S. Pat. No. 3,639,542. Preferredpolyhydroxyl-containing phosphorus compounds are prepared from alkyleneoxides and acids of phosphorus having a P₂ O₅ equivalency of from about72 percent to about 95 percent.

Suitable polyacetals which may be condensed with alkylene oxides includethe reaction product of formaldehyde or other suitable aldehyde with adihydric alcohol or an alkylene oxide such as those disclosed above.

Suitable aliphatic thiols which may be condensed with alkylene oxidesinclude alkanethiols containing at least two -SH groups such as1,2-ethanedithiol, 1,2-propanedithiol, 1,2-propanedithiol, and1,6-hexanedithiol; alkene thiols such as 2-butene-1,4-dithiol; andalkyne thiols such as 3-hexyne-1,6-dithiol.

Also suitable for mixture with the compound having polyester linkagesare polymer modified polyols, in particular, the so-called graftpolyols. Graft polyols are well known to the art and are prepared by thein situ polymerization of one or more vinyl monomers, preferablyacrylonitrile and styrene, in the presence of a polyether or polyesterpolyol, particularly polyols containing a minor amount of natural orinduced unsaturation. Methods of preparing such graft polyols may befound in columns 1-5 and in the Examples of U.S. Pat. No. 3,652,639; incolumns 1-6 and the Examples of U.S. Pat. No. 3,823,201; particularly incolumns 2-8 and the Examples of U.S. Pat. No. 4,690,956; and in U.S.Pat. No. 4,524,157; all of which patents are herein incorporated byreference.

Non-graft polymer modified polyols can also be mixed, for example, thoseprepared by the reaction of a polyisocyanate with an alkanolamine in thepresence of a polyol as taught by U.S. Pat. Nos. 4,293,470; 4,296,213;and 4,374,209; dispersions of polyisocyanurates containing pendant ureagroups as taught by U.S. Pat. No. 4,386,167; and polyisocyanuratedispersions also containing biuret linkages as taught by U.S. Pat. No.4,359,541. Other polymer modified polyols may be prepared by the in situsize reduction of polymers until the particle size is less than 20 μm ,preferably less than 10 μm.

The polyol composition, in addition to the polyol having polyesterlinkages, may also contain any of the above mentioned polyols such aspolyether polyols, as well as an organo-phosphorus compounds having atleast two isocyanate reactive hydrogens. The organo-phosphorus compoundshaving at least two isocyanate active hydrogens are reactive with theisocyanate to form part of the polyurethane matrix, thereby promotinggood char formation without collapse of the charred surface into freshfoam which can burn. The foams contain phosphorus atoms covalentlybonded through one or more carbon atoms and/or oxygen atoms to aurethane group, thereby forming a part of the foam matrix. The reactiveorgano-phosphorus compound used in the invention may be distinguishedfrom organo-phosphorus additives which are non-reactive with anisocyanate group because the latter do not form a part of thepolyurethane matrix through covalent bonding to a urethane group.

These organo-phosphorus compounds have at least two isocyanate reactivehydrogens such as thio groups, amino groups, hydroxyl groups, ormixtures thereof. Preferred are the organo-phosphorus polyols.Illustrative organo-phosphorus polyols which may be employed in thepolyol composition of the present invention include phosphate polyols,phosphite polyols, phosphonate polyols, phosphinate polyols,phosphoramidates, polyphosphorus polyols, phosphinyl polyether polyols,and polyhydroxyl-containing phosphine oxides.

Typical phosphate polyols are those prepared by (1) by the reaction ofalkylene oxides with (a) phosphoric acids having a P₂ O₅ equivalency offrom 72 to 95 percent, (b) partial esters of these acids, or (c) estersprepared by the reaction of phosphorus pentoxide and alcohols; (2) bythe oxidation of phosphites prepared by the reaction of trialkylphosphites with polyhydroxyl-containing materials; and (3) bytransesterifying the reaction products of (1) and (2). The preparationof these neutral phosphate polyols is known in the art as evidence byU.S. Pat. Nos. 3,375,305; 3,369,060; 3,324,202; 3,317,639; 3,317,510;3,099,676; 3,081,331; 3,061,625; 2,909,559; 3,417,164; and 3,393,254.

Also useful are the phosphite polyols, which are meant to also includethe diphosphites and the polyphosphite polyol compounds, optionallycontaining polyphosphates. Typical phosphite polyols are those prepared(1) by the reaction of alkylene oxides with phosphorus acid, (2) by thereaction of trialkylphosphites with polyhydroxyl-containing materials,and (3) by transesterifying the reaction products of (1) and (2). Thepreparation of these phosphite polyols is known in the art as evidencedby U.S. Pat. Nos. 3,359,348; 3,354,241; 3,352,947; 3,351,683; 3,320,337;3,281,502; 3,246,051; 3,081,331; and 3,009,939; each incorporated hereinby reference.

Another group of useful phosphite polyols are the trialkyl phosphitepolyols where each of the alkyl groups of the trialkyl phosphitesindependently have 1 to 20 carbon atoms, preferably 1 to 8. In oneembodiment, the polyphosphite polyol has the general formula: ##STR2##where R is the alkylene glycol or polyalkylene glycol residue, and R₁ isthe alkyl residue from the trialkyl phosphite, and X is from 1 to 50.Suitable trialkyl phosphites from which the polyol may be derivedinclude triisodecyl phosphite, triisoctyl phosphite, trilaurylphosphite, tristearyl phosphite, tri- methyl, ethyl, propyl, butyl, etc.phosphites, unsaturated phosphites such as triallyl phosphite, and mixedphosphites such as methyldiethyl phosphite and ethyldibutyl phosphite.Also included are the aryl-substituted phosphites.

Typical phosphonate polyols are those prepared (1) by the reaction ofalkylene oxides with phosphonic acid, (2) by the reaction of phosphitepolyols with alkyl halides, (3) by the condensation of dialkylphosphites with alkanolamines and formaldehyde, and (4) bytransesterifying the products of (1), (2), and (3). The preparation ofthese phosphonate polyols is known in the art as evidenced by U.S. Pat.Nos. 3,349,150; 3,330,888; 3,342,651; 3,139,450; and 3,092,651.

Typical phosphinate polyols include (1) hydroxyalkyl phosphinic acids,(2) reaction products of alkylene oxides and hydroxyalkyl phosphinicacids, and (3) transesterified reaction products of (2). The preparationof these phosphinate polyols is known in the art as evidenced by U.S.Pat. No. 3,316,333.

Typical phosphoramidates include those disclosed in U.S. Pat. Nos.3,335,129; 3,278,653; and 3,088,9661. Typical polyhydroxyl-containingphosphine oxides include the di-and tri-substituted hydroxylalkylphosphine oxides such as trihydroxylmethyl phosphine oxides.

Also useful are the polyphosphorus compounds such as polyoxyalkylenepolyether polyphosphorus compounds where the polyphosphorus atoms formpart of the backbone chain. Illustrative examples are found in U.S. Pat.No. 3,878,270, which describes a polyalkylene glycol polyphosphoruscompound having both phosphite and vinylphosphate linkages. Otherexamples include the polyphosphorus compounds described in U.S. Pat.Nos. 4,094,926; 3,989,652; 3,840,622; 3,764,640; and 3,767,732. Thesepatents are in their entirety incorporated herein by reference.

Phosphinyl polyether polyols similar to the ones above which are usefulin the invention are described in U.S. Pat. Nos. 3,660,314; 3,682,988;3,760,038; incorporated herein by reference. Such polyols includepolyether polyols substituted with organic phosphite groups, organicphosphonite groups, organic phosphinite groups, cyclic phosphite groups,which groups optionally are hydrolyzed to increase the hydroxylfunctionality of the polyether polyol. These phosphinyl polyetherpolyols may be prepared by reacting a polyether polyol having a halogenwith an organic phosphonite, phosphinite, or cyclic phosphite compound,where the halogen is replaced by phosphinyl groups.

Aromatic amino polyols containing phosphorus atoms are also useful anddescribed in U.S. Pat. No. 4,681,965. Such polyols are prepared by theMannich condensation reaction between a phenol, formaldehyde, a primaryamine, and an alkanol phosphite. Other aliphatic amino polyolscontaining phosphorus atoms are described in U.S. Pat. Nos. 3,076,010and 4,052,487. Each of these patents are incorporated herein byreference.

As a second ingredient used to make the polyurethane foam of theinvention, there is provided a b) aliphatic or cycloaliphatic C₄ -C₇hydrocarbon blowing agent. The blowing agent should have a boiling pointof 50° C. or less at one atmosphere, preferably 38° C. or less. Thehydrocarbon blowing agent may form part of the polyol composition bymixing the hydrocarbon into the polyols prior to foaming, or thehydrocarbon may be mixed with the isocyanate, or both. Generally, thehydrocarbon will be mixed into the polyol composition and form part ofthe polyol composition immediately prior (within the hour) to reactingthe foaming reaction because the hydrocarbons are not very soluble, orcompletely insoluble, in many polyols used to make polyurethane foams.There may exist some polyols, however, or compatabilizing agents whichwould be soluble with or bring the hydrocarbons into an emulsion orsolution with the polyols, thereby allowing the hydrocarbon to be addedto the polyol composition days or weeks prior to the foaming reactionwithout phase separation.

The hydrocarbon is physically active and has a sufficiently low boilingpoint to be gaseous at the exothermic temperatures caused by thereaction between the isocyanate and polyols, so as to foam the resultingpolyurethane matrix. The hydrocarbon blowing agents consist exclusivelyof carbon and oxygen, therefore, they are non-halogenated by definition.Examples of the C₄ -C₇ hydrocarbon blowing agents include linear orbranched alkanes, e.g. butane, isobutane, 2,3 dimethylbutane, n- andisopentane and technical-grade pentane mixtures, n- and isohexanes, andn- and isoheptanes. Specific examples of alkenes are 1-pentene,2-methylbutene, 3-methylbutene, and 1-hexene, and of cycloalkanes arecyclobutane, preferably cyclopentane, cyclohexane or mixtures thereof.Preferentially, cyclopentane, n- and isopentane, (including theirtechnical grades) and mixtures thereof are employed.

Other blowing agents which can be used in combination with the one ormore C₄ -C₇ hydrocarbon blowing agents may be divided into thechemically active blowing agents which chemically react with theisocyanate or with other formulation ingredients to release a gas forfoaming, and the physically active blowing agents which are gaseous atthe exotherm foaming temperatures or less without the necessity forchemically reacting with the foam ingredients to provide a blowing gas.Included with the meaning of physically active blowing agents are thosegases which are thermally unstable and decompose at elevatedtemperatures.

Examples of chemically active blowing agents are preferentially thosewhich react with the isocyanate to liberate gas, such as CO₂. Suitablechemically active blowing agents include, but are not limited to, water,mono- and polycarboxylic acids having a molecular weight of from 46 to300, salts of these acids, and tertiary alcohols.

Water is preferentially used as a co-blowing agent with the hydrocarbonblowing agent. Water reacts with the organic isocyanate to liberate CO₂gas which is the actual blowing agent. However, since water consumesisocyanate groups, an equivalent molar excess of isocyanate must be usedto make up for the consumed isocyanates.

The organic carboxylic acids used are advantageously aliphatic mon- andpolycarboxylic acids, e.g. dicarboxylic acids. However, other organicmono- and polycarboxylic acids are also suitable. The organic carboxylicacids may, if desired, also contain substituents which are inert underthe reaction conditions of the polyisocyanate polyaddition or arereactive with isocyanate, and/or may contain olefinically unsaturatedgroups. Specific examples of chemically inert substituents are halogenatoms, such as fluorine and/or chlorine, and alkyl, e.g. methyl orethyl. The substituted organic carboxylic acids expediently contain atleast one further group which is reactive toward isocyanates, e.g. amercapto group, a primary and/or secondary amino group, or preferably aprimary and/or secondary hydroxyl group.

Suitable carboxylic acids are thus substituted or unsubstitutedmonocarboxylic acids, e.g. formic acid, acetic acid, propionic acid,2-chloropropionic acid, 3-chloropropionic acid, 2,2-dichlorpropionicacid, hexanoic acid, 2-ethyl-hexanoic acid, cyclohexanecarboxylic acid,dodecanoic acid, palmitic acid, stearic acid, oleic acid,3-mercapto-propionic acid, glycoli acid, 3-hydroxypropionic acid, lacticacid, ricinoleic acid, 2-aminopropionic acid, benzoic acid,4-methylbenzoic acid, salicylic acid and anthranilic acid, andunsubstituted or substituted polycarboxylic acids, preferablydicarboxylic acids, e.g. oxalic acid, malonic acid, succinic acid,fumaric acid, maleic acid, glutaric acid, adipic acid, sebacic acid,dodecanedioic acid, tartaric acid, phthalic acid, isophthalic acid andcitric acid. Preferable acids are formic acid, propionic acid, aceticacid, and 2-ethylhexanoic acid, particularly formic acid.

The amine salts are usually formed using tertiary amines, e.g.triethylamine, dimethylbenzylamine, diethylbenzylamine,triethylenediamine, or hydrazine. Tertiary amine salts of formic acidmay be employed as chemically active blowing agents which will reactwith the organic isocyanate. The salts may be added as such or formed insitu by reaction between any tertiary amine (catalyst or polyol) andformic acid contained in the polyol composition.

Combinations of any of the aforementioned chemically active blowingagents may be employed, such as formic acid, salts of formic acid,and/or water.

Physically active blowing agents are those which boil at the exothermfoaming temperature or less, preferably at 50° C. or less at 1atmosphere. The most preferred physically active blowing agents arethose which have an ozone depletion potential of 0.05 or less. Examplesof other physically active blowing agents are dialkyl ethers,cycloalkylene ethers and ketones; hydrochlorofluorocarbons (HCFCs);hydrofluorocarbons (HFCs); perfluorinated hydrocarbons (HFCs);fluorinated ethers (HFCs); and decomposition products.

Any hydrochlorofluorocarbon blowing agent may be used in the presentinvention. Preferred hydrochlorofluorocarbon blowing agents include1-chloro-1,2-difluoroethane; 1-chloro-2,2-difluoroethane (142a);1-chloro-1,1-difluoroethane (142b); 1,1-dichloro-1-fluoroethane (141b);1-chloro-1,1,2-trifluoroethane; 1-chloro-1,2,2-trifluoroethane;1,1-diochloro-1,2-difluoroethane; 1-chloro-1,1,2,2-tetrafluoroethane(124a); 1-chloro-1,2,2,2-tetrafluoroethane (124);1,1-dichloro-1,2,2-trifluoroethane; 1,1-dichloro-2,2,2-trifluoroethane(123); and 1,2-dichloro-1,1,2-trifluoroethane (123a);monochlorodifluoromethane (HCFC-22); 1-chloro-2,2,2-trifluoroethane(HCFC-133a); gem-chlorofluoroethylene (R-1131a);chloroheptafluoropropane (HCFC-217); chlorodifluoroethylene (HCFC-1122);and trans-chlorofluoroethylene (HCFC-1131). The most preferredhydrochlorofluorocarbon blowing agent is 1,1-dichloro-1-fluoroethane(HCFC-141b).

Suitable hydrofluorocarbons, perfluorinated hydrocarbons, andfluorinated ethers include difluoromethane (HFC-32);1,1,1,2-tetrafluoroethane (HFC-134a); 1,1,2,2-tetrafluoroethane (HFC-134); 1,1 -difluoroethane (HFC- 152a); 1,2-difluoroethane (HFC- 142),trifluoromethane; heptafluoropropane; 1,1,1-trifluoroethane;1,1,2-trifluoroethane; 1,1,1,2,2-pentafluoropropane;1,1,1,3-tetrafluoropropane; 1,1,2,3,3-pentafluoropropane;1,1,1,3,3-pentafluoro-n-butane; hexafluorocyclopropane (C-216);octafluorocyclobutane (C-318); perfluorotetrahydrofuran; perfluoroalkyltetrahydrofurans; perfluorofuran; perfluoro-propane, -butane,-cyclobutane, -pentane, -cyclopentane, and -hexane, -cyclohexane,-heptane, and -octane; perfluorodiethyl ether; perfluorodipropyl ether;and perfluoroethyl propyl ether.

Decomposition type physically active blowing agents which release a gasthrough thermal decomposition include pecan flour, amine/carbon dioxidecomplexes, and alkyl alkanoate compounds, especially methyl and ethylformates.

There may also be mentioned as a blowing agent a mono-halogenatedhydrocarbon having from three to six carbon atoms. More specifically,one may use a secondary or tertiary mono-halogenated aliphatichydrocarbon blowing agent having three (3) to six (6) carbon atoms,which enables the halogen to disassociate from the hydrocarbon as a freeradical. The halogen atom is a secondary or tertiary halogen atom on thecarbon backbone. The hydrocarbon itself may be substituted with alkylgroups. Examples of suitable mono-halogenated hydrocarbons that may beused a co-blowing agents in conjunction with the aliphatic orcycloaliphatic C₄ -C₇ hydrocarbon include 2-chloropropane,2-chlorobutane, tertiary butyl chloride, and the iodine, fluorine, orbromine halogen substituted compounds of the foregoing, preferably asecondary mono-halogenated aliphatic hydrocarbon with 3 to 4 carbonatoms, further with chlorine as the halogen. The most preferred compoundin this class is 2-chloropropane.

The total and relative amounts of blowing agents will depend upon thedesired foam density, the type of hydrocarbon, and the amount and typeof additional blowing agents employed. Polyurethane foam densitiestypical for rigid polyurethane insulation applications range from freerise densities of 1.3 to 2.5 pcf, preferably from 1.3 to 2.1 pcf, andoverall molded densities of 1.5 to 3.0 pcf. The amount by weight of allblowing agents is generally 10 php to 40 php, preferably 20 php to 35php (php means parts per hundred parts of all polyols). Based on theweight of all the foaming ingredients, the total amount of blowing agentis generally from 4 wt % to 15 wt %. The amount of hydrocarbon blowingagent, based on the weight of all the foaming ingredients, is also from4 wt. % to 15 wt %, preferably from 6 wt % to 10 wt %.

Water is typically found in minor quantities in the polyols as abyproduct and may be sufficient to provide the desired blowing from achemically active substance. Preferably, however, water is additionallyintroduced into the polyol composition in amounts from 0.05 to 5 php,preferably from 0.25 to 1.0 php.

As the third ingredient in the polyol composition, there is asilicone-containing polymer surfactant. This polymer will generallycontain the moiety, --Si(R₂)O--, where the R groups are independently analkyl radical having 1 to 20 carbon atoms; an alicyclic, an aryl, analkaryl or an aralkyl having 1 to 25 carbon atoms in the alkyl group; analiphatic ether group; or a polyester group, preferably an alkyl radicalhaving from 1 to 4 carbon atoms. The silicon-containing polymer utilizedin the invention can be hydroxyl functional such as a polymer modifiedwith polyoxyalkylene polyether groups terminated with hydroxyl groups,or alternatively and more preferably are those silicone-containingpolymers modified with polyoxyalkylene polyether groups terminated withhydrocarbon groups, which are non-reactive with the organic isocyanate.

The hydroxyl functional silicone polymer can contain two or moresecondary hydroxyl groups, and more preferably an average of threehydroxyl groups per silicon-containing polymer molecule. In one aspectof the invention, the silicon-containing polymer is a dimethylsiloxanecompound which is represented by the following generic formula: ##STR3##wherein each of R are independently an alkyl radical having 1 to 20carbon atoms; an alicyclic, an aryl, an alkaryl or an aralkyl having 1to 25 carbon atoms in the alkyl group; an aliphatic ether group; or apolyester group; and wherein a secondary hydroxyl functional group issubstituted onto at least two, preferably onto each of the R groups;

each of A are independently one or more silicon atoms containing alkyl,alicyclic, cycloalkyl, aryl, alkyloxy, alkaryl, aralkyl, or arylalkoxyhave a 1 to 25 carbon atoms in each aliphatic portion; anorganosiloxane; hydrogen; or an alkyl having 1 to 25 carbon atoms;

the sum of w+x totals an integer which would correspond to a polymerhaving an average hydroxyl equivalent weight ranging from 200 to 4,000.

Preferably, each of R are independently an alkyl having from 1 to 10carbon atoms, an alkoxy, or an ether having the formula: ##STR4## andpreferably A is hydrogen, a C₁ -C₄ alkyl, or a siloxane having theformula: ##STR5## wherein n is an integer from 1 to 6, and w+x+y+ztotals an integer corresponding to an average hydroxyl equivalent weightof the molecule ranging from 1,250 to 3,000.

One example of a hydroxyl functional polymer is represented by theformula: ##STR6## wherein R¹ groups are the same or different andrepresent alkyl groups with 1 to 4 carbon atoms, phenyl groups, orgroups with the formula: ##STR7## R₂ groups can have the same meaning asthe R₁ groups, with the proviso that at least one R₂ group is a hydroxylfunctional C₁ -C₈ hydrocarbon or one or more oxyalkylene groupsterminated with a hydroxyl group;

a has a value of 1 to 1000; and

b has a value of 0 to 10.

A species of the above identified hydroxyl functional silicone polymercorresponds with the formula: ##STR8## wherein each n is independentlyan integer ranging from 1 to 4, and w+x+y+z is about 70, or correspondsto average hydroxyl equivalent weight of a molecule of about 2,000. Themethods of manufacture of such silicone-containing hydroxyl functionalpolymers and the polymer products are generally described in U.S. Pat.Nos. 4,130,708 and 5,391,679, the disclosure of which each are herebyincorporated by reference.

Also useful as the silicone polymer used in the invention are thepolysiloxane-oxyalkylated polymers terminated with hydrocarbon groups.Examples of such surfactants include the branched organosiliconpolyglycol block copolymers having a weight average molecular weight ofless than about 30,000. Such surfactants include thepoly(dimethyl)siloxane polyoxyalkylene copolymers having a weightaverage molecular weight of preferably less than 10,000, with a dimethylsiloxane content of from about 15% to about 40% by with of the totalpolymer and an oxyethylene content of greater than about 60, mostpreferably about 100 weight percent of the polyoxyalkylene glycol moietyand an oxyethylene content greater than about 40% of the totalsurfactant polymer.

Specific examples of polysiloxane-oxyalkylated polymers terminated withhydrocarbon groups include the L series supplied by Union Carbide, suchas L-5340, L-5420, and L-5440. Other examples include LK-221 and LK-448from Air Products and Chemicals Co.

In one embodiment, the silicone surfactants (hereinafter calledsiloxane-oxyalkylene copolymer A) are hydrolyzable siloxane-oxyalkylenecopolymers (hereinafter called siloxane-oxyalkylene copolymer A-1)expressed by the general formula (I):

    (R')(SiO.sub.3).sub.x (R.sub.2 SiO).sub.y  (CnH.sub.2n O).sub.z R"!.sub.a  R!.sub.3x-a

wherein x is an integer of at least 1 and stands for the number oftrifunctional silicon atoms; y is an integer of at least 3 and standsfor the number of difunctional siloxane units; z is an integer of atleast 5 and stands for the length of a polyoxyalkylene chain; a is aninteger and stands for the number of polyoxyalkylene units; n is aninteger of 2 to 4 and stands for the number of carbon atoms in anoxyalkylene group; R' is a monovalent hydrocarbon group, e.g., a C₁ -C₆alkyl or an aralkyl group; R" is a monovalent hydrocarbon group, e.g.,alkyl or aralkyl, forming a monoether group at the end of an alkylenechain; and each R group is independently an alkyl group, such as a C₁-C₆ alkyl, or a trihydrocarbylsilyl group at an end of a siloxane group,the polymer being characterized by containing 10 to 80 percent by weightpolysiloxane units and 90 to 20 percent by weight of polyoxyalkyleneunits, having polysiloxane chains and polyoxyalkylene chains bonded witha C--O--Si bond and having a molecular weight of 1,000 to 16,000.

Alternatively, as siloxane-oxyalkylene copolymer A in the presentinvention can also be used a non-hydrolyzable siloxane-oxyalkylenecopolymer (hereinafter called siloxane-oxyalkylene copolymer A-II)expressed by the general formula (II):

    R'.sub.3 SiO(R.sub.2 SiO).sub.y  RO(CnH.sub.2n O).sub.z SiRO!.sub.w SiR.sub.3

wherein w is an integer of at least 1, y is an integer of at least 3 andstands for the number of difunctional siloxane units; z is an integer ofat least 5 and stands for the length of a polyoxyalkylene chain; n is aninteger of 2 to 4 and stands for the number of carbon atoms in anoxyalkylene group; each of R' and each R are independently the same asdefined in the above formula (I), the polymer being characterized bycontaining 5 to 95 percent by weight, preferably 5 to 50 percent byweight of polysiloxane units and 95 to 5 percent by weight, preferably95 to 50 percent by weight of polyoxyalkylene units, having apolysiloxane chain and a polyoxyalkylene chain bonded with a C--Si bond(instead of a C--O--Si bond) and having a molecular weight of 1,000 to16,000.

As a specific example of a species of copolymer A-II, there can bementioned a polymer corresponding to the formula: ##STR9## wherein w, y,z, n, and R are as defined above. The y and y' together are as definedby the y group above, such that the sum of y and y' must be at least 3and each are at least 1. The p groups are independently integers from 2to 17. Methods of manufacturing this polymer are described in U.S. Pat.No. 4,698,178, incorporated herein by reference.

As an example of a low molecular weight siloxane-oxyalkylene copolymer(hereinafter called siloxane-oxyalkylene copolymer B) there can bementioned a hydrolyzable siloxane-oxyalkylene copolymer (hereinaftercalled siloxane-oxyalkylene copolymer B-I) expressed by the generalformula (III):

    (R')(SiO.sub.3).sub.x (R.sub.2 SiO).sub.y  (CnH.sub.2n O).sub.z R"!.sub.a  R!.sub.3x-a

where x is an integer of at least 1 and stands for the number oftrifunctional silicon atoms; y is an integer of at least 3 and standsfor the number of difunctional siloxane units; z is an integer of 0 or 1to 4 and stands for the length of a polyoxyalkylene chain; a is aninteger and stands for the number of polyoxyalkylene units; n is aninteger of 2 to 4 or mixtures thereof, and stands for the number ofcarbon atoms in an oxyalkylene group; R' is an x-valent hydrocarbongroup, e.g., when x is 1, a monovalent hydrocarbon group such as alkyland when x is 2, a divalent hydrocarbon group such as alkylene; R" is amonovalent hydrocarbon group such as alkyl, aryl or aralkyl and forms amonoether group at the end of a polyoxyalkylene chain; and R is an alkylgroup or trihydrocarbylsilyl group at an end of a siloxane group. Thepolymer is characterized by containing more than 80 percent by weight ofpolysiloxane units and less than 20 percent by weight of polyoxyalkyleneunits, having a polysiloxane chain and a polyoxyalkylene chain bondedwith a C--O--Si bond and having a molecular weight of 500 to 10,000.

Alternatively, as siloxane-oxyalkylene copolymer B in the presentinvention can also be used a non-hydrolyzable siloxane-oxyalkylenecopolymer (hereinafter called siloxane-oxyalkylene copolymer B-II)expressed by the general formula (IV):

    R'.sub.3 SiO(R.sub.2 SiO).sub.y  RO(CnH.sub.2n O)zRO!.sub.w SiR.sub.3

where w is an integer of at least 1, 6, z, n, and R and R' are the sameas defined in the above formula (III), characterized by containing morethan 95 percent by weight of polysiloxane units and less than 5 percentby weight of polyoxyalkylene units, having a polysiloxane chain and apolyoxyalkylene chain bonded with a C--Si bond (instead of a C--O--Sibond) and having a molecular weight of 500 to 10,000. The abovepolysiloxane-polyoxyalkylene copolymers are described in U.S. Pat. No.4,119,582.

The siloxane-oxyalkylene copolymer may be prepared by reacting amonoalkylene ether, preferably the allyl ether, of the desiredpolyoxyalkylene glycol with a siloxane containing SiH group.

The reaction is carried out by heating a mixture of the two reactants inthe presence of a platinum catalyst such as chloroplatinic aciddissolved in a small amount of isopropyl alcohol, at temperatures from100° to 200° C.

The siloxanes can be of four formulae:

    R.sub.a Si (OSiMe.sub.2).sub.n (OSiMeH).sub.d OSiMe.sub.2 H!.sub.4-a

    HMe.sub.2 Si(Osime.sub.2).sub.n (Osimeh).sub.b OSiMe.sub.2 H

    Me.sub.3 Si(Osime.sub.2).sub.n (Osimeh).sub.c OSiMe.sub.3 and

    R.sub.a Si (Osime.sub.2).sub.n (Osimeh).sub.c OSiMe.sub.3 !.sub.4-a

wherein R is a hydrocarbon radical free of aliphatic unsaturation andcontains from 1 to 10 carbon atoms. Me is a methyl radical; a has anaverage value from 0-1; n has an average value from 6-240; d has anaverage value from 0-30; b has an average value from 1-30; and c has anaverage value from 3-30 to the extent that the ratio of total Me₂ SiOunits to total ##STR10## units is within the range of 3.5:1 to 15:1,wherein G is a radical of the structure --D(OR")_(Ma) wherein D is analkylene radical containing from 1 to 30 carbons atoms, A is a radicalselected from the group consisting of the --OR', --OOCR', and --OCOR'radicals wherein R' is a hydrocarbon radical free of aliphaticunsaturation selected from the group consisting of hydrocarbon andradicals, the A radical containing a total of less than 11 atoms, R" iscomposed of oxyalkylene radicals such as ethylene, propylene, andbutylene radicals, the amount of ethylene radicals relative to the otheralkylene radicals being such that the ratio of carbon atoms to oxygenatoms in the total OR" block ranges from 2.3:1 to 2.8:1, and m has anaverage value from 25 to 100.

Any of the siloxanes 1-4 or mixtures of siloxanes 1-4 can be utilizedwhich give rise to a copolymer when reacted with an unsaturated glycol,in which the ratio of total Me₂ SiO units to total ##STR11## units arederived from the corresponding SiH units so that the same ratio of Me₂SiO units to SiH units prevails as for the Me₂ SiO units to ##STR12##units.

The above siloxanes are prepared by cohydrolyzing the appropriatesiloxanes as for instance in (1) above, a mixture of silanes such asR_(a) SiX_(4-a) with dimethyldichlorosilane, methyldichlorosilane, anddimethylmonochlorosilane, and thereafter equilibrating the cohydrolyzatewith an acid catalyst such as H₂ SO₄. Number (2) is prepared bycohydrolyzing the silanes in portion of n moles ofdimethyldichlorosilane, two moles of dimethylmonochlorosilane, and bmoles of methyldichlorosilane. Once again the hydrolyzate is H₂ SO₄equilibrated. Number (3) is prepared by cohydrolyzing the silanes in theproportion of n moles of dimethyldichlorosilane, two moles oftrimethylmonochlorosilane and c moles of methyldichlorosilane. Onceagain the hydrolyzate is H₂ SO₄ equilibrated. Number (4) is prepared bycohydroxylyzing one mole of silane of the formula R_(a) SiX_(4-a) with nmoles of dimethyldichlorosilane, c moles of methyldichlorosilane andthereafter equilibrating with H₂ SO₄. In such case, X is chlorine.

Another method of preparing the siloxanes is to equilibrate siloxanesthat have already been hydrolyzed. Such a method for instance wouldinvolve the equilibration at temperatures in excess of 50° C., a mixtureof n units of Me₂ SiO in the form of octamethylcyclotetrasiloxane, bunits of (MeHSiO) in the form of (MeHSiO)₄ and 1 unit of (Hme₂ Si)₂ O inthe presence of an equilibrating catalyst. Such equilibrating catalystsare known in the art and consist of acid clays, acid treated melaminetype resins and fluorinated alkanes with sulfonic acid groups. For thoseunfamiliar with such preparations, they can be found in detail in U.S.Pat. No. 3,402,192, and that patent is hereby incorporated by reference.

The monoalkylene ether of the desired polyoxyalkylene glycol can be acopolymer of ethylene oxide and propylene oxide or copolymers ofethylene oxide and butylene oxide or can be copolymers of all threeoxides. The ratio of ethylene radicals relative to the other alkyleneradicals should be such that the ratio of carbon atoms to oxygen atomsin the glycol copolymer ranges from 2.3:1 to 2.8:1. In addition, theends of the polyglycol chain not attached to the siloxane moiety have agroup A wherein A is defined above.

These glycol copolymers can be linear or branched and can contain anynumber of carbon atoms.

One method of preparing the glycol copolymers is to dissolve sodiummetal in allyl alcohol in a mole ratio of one to one and reacting theresulting product with the appropriate oxides at elevated temperaturesand under pressure. The resulting product, after purification by removalof low boilers, is then capped with the appropriate group A.

The siloxane-oxyalkylene copolymer is then prepared by reacting theappropriate siloxane precursor and the appropriate polyglycol copolymerat elevated temperatures in the presence of platinum as the catalyst anda solvent if desired. These polysiloxane-polyoxyalkylene copolymers aredescribed in U.S. Pat. No. 4,147,847.

Other types of silicone containing polymers within the scope of theinvention include the so called inverted polymers wherein thepolyoxyalkylene chain forms the backbone of the polymer and thepolysiloxane chains form the pendant or terminal groups. Such structuresand methods of preparation are described in U.S. Pat. No. 5,045,571,incorporated herein by reference.

The silicone-containing polymer is used in amounts of at least about 8php (parts per hundred parts of polyol). At lower levels conventionallyused in polyurethane/polyisocyanurate foam formulations, i.e. 2 php, theflame retardancy and thermal conductivity of the hydrocarbon blown foamsof the present invention are not affected. Surprisingly, it was only atthe higher levels of about 8 php or more that the mechanical propertiesof the foam across the board improved significantly, that is, the flameretardance, the aged thermal conductivity, the compressive strength, andthe friability. For example, at levels of 6 php of surfactant, there wasno significant improvement in the mechanical properties of the foam ascompared to when 8 php of the silicone polymer surfactant was used. Theupper level on the amount of surfactant used is not limited except thatfor cost considerations, the amount should be kept as low as possiblewhile obtaining the beneficial effects of the silicone-polymer.

Additional optional ingredients in the polyol composition may includeisocyanate and/or isocyanurate promoting catalysts, flame retardants,and fillers.

Catalysts may be employed which greatly accelerate the reaction of thecompounds containing hydroxyl groups and with the modified or unmodifiedpolyisocyanates. Examples of suitable compounds are cure catalysts whichalso function to shorten tack time, promote green strength, and preventfoam shrinkage. Suitable cure catalysts are organometallic catalysts,preferably organotin catalysts, although it is possible to employ metalssuch as lead, titanium, copper, mercury, cobalt, nickel, iron, vanadium,antimony, and manganese. Suitable organometallic catalysts, exemplifiedhere by tin as the metal, are represented by the formula: R_(n) Sn X-R¹-Y!₂, wherein R is a C₁ -C₈ alkyl or aryl group, R¹ is a C₀ -C₁₈methylene group optionally substituted or branched with a C₁ -C₄ alkylgroup, Y is hydrogen or an hydroxyl group, preferably hydrogen, X ismethylene, an --S--, an --SR² COO--, --SOOC--, an --0₃ S--, or an--OOC-- group wherein R² is a C₁ -C₄ alkyl, n is 0 or 2, provided thatR¹ is C₀ only when X is a methylene group. Specific examples are tin(II) acetate, tin (II) octanoate, tin (II) ethylhexanoate and tin (II)laurate; and dialkyl (1-8C) tin (IV) salts of organic carboxylic acidshaving 1-32 carbon atoms, preferably 1-20 carbon atoms, e.g., diethyltindiacetate, dibutyltin diacetate, dibutyltin diacetate, dibutyltindilaurate, dibutyltin maleate, dihexyltin diacetate, and dioctyltindiacetate. Other suitable organotin catalysts are organotin alkoxidesand mono or polyalkyl (1-8C) tin (IV) salts of inorganic compounds suchas butyltin trichloride, dimethyl- and diethyl- and dibutyl- anddioctyl- and diphenyl- tin oxide, dibutyltin dibutoxide,di(2-ethylhexyl) tin oxide, dibutyltin dichloride, and dioctyltindioxide. Preferred, however, are tin catalysts with tin-sulfur bondswhich are resistant to hydrolysis, such as dialkyl (1-20C) tindimercaptides, including dimethyl-, dibutyl-, and dioctyl- tindimercaptides.

Tertiary amines also promote urethane linkage formation, and includetriethylamine, 3-methoxypropyldimethylamine, triethylenediamine,tributylamine, dimethylbenzylamine, N-methyl-, N-ethyl- andN-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine,N,N,N',N'-tetramethylbutanediamine or -hexanediamine, N,N,N'-trimethylisopropyl propylenediamine, pentamethyldiethylenetriamine,tetramethyldiaminoethyl ether, bis(dimethylaminopropyl)urea,dimethylpiperazine, 1-methyl4-dimethylaminoethylpiperazine,1,2-dimethylimidazole, 1-azabicylo 3.3.0!octane and preferably1,4-diazabicylo 2.2.2!octane, and alkanolamine compounds, such astriethanolamine, triisopropanolamine, N-methyl- andN-ethyldiethanolamine and dimethylethanolamine.

To prepare the polyisocyanurate (PIR) and the PUR-PIR foams of theinvention, a polyisocyanurate catalyst is employed. Suitablepolyisocyanurate catalysts are alkali salts, for example, sodium salts,preferably potassium salts and ammonium salts, of organic carboxylicacids, expediently having from 1 to 8 carbon atoms, preferably 1 or 2carbon atoms, for example, the salts of formic acid, acetic acid,propionic acid, or octanoic acid, and tris(dialkylaminoethyl)-,tris(dimethylamninopropyl)-, tris(dimethylaminobutyl)- and thecorresponding tris(diethylaminoalkyl)-s-hexahydrotriazines. However,(trimethyl-2-hydroxypropyl) ammonium formate,(trimethyl-2-hydroxypropyl)ammonium octanoate, potassium acetate,potassium formate and tris(dimethylamninopropyl)-s-hexahydrotriazine arepolyisocyanurate catalysts which are generally used. The suitablepolyisocyanurate catalyst is usually used in an amount of from 1 to 10php, preferably from 1.5 to 8 php.

Examples of suitable flame retardants are tetrakis(2-chloroethyl)ethylene phosphonate, tris(1,3-dichloropropyl) phosphate,tris(beta-chloroethyl) phosphate, tricresyl phosphate,tris(2,3-dibromopropyl)phosphate,tris(beta-chloropropyl)phosphate,tricresyl phosphate, andtris(2,3-dibromopropyl) phosphate.

In addition to the above-mentioned halogen-substituted phosphates, it isalso possible to use inorganic or organic flameproofing agents, such asred phosphorus, aluminum oxide hydrate, antimony trioxide, arsenicoxide, ammonium polyphosphate (Exolit®) and calcium sulfate, expandablegraphite or cyanuric acid derivatives, e.g., melamine, or mixtures oftwo or more flameproofing agents, e.g., ammonium polyphosphates andmelamine, and, if desired, corn starch, or ammonium polyphosphate,melamine, and expandable graphite and/or, if desired, aromaticpolyesters, in order to flameproof the polyisocyanate polyadditionproducts. In general, from 2 to 50 php, preferably from 5 to 25 php, ofsaid flameproofing agents may be used.

Optional fillers are conventional organic and inorganic fillers andreinforcing agents. Specific examples are inorganic fillers, such assilicate minerals, for example, phyllosilicates such as antigorite,serpentine, hornblendes, amphiboles, chrysotile, and talc; metal oxides,such as kaolin, aluminum oxides, titanium oxides and iron oxides; metalsalts, such as chalk, baryte and inorganic pigments, such as cadmiumsulfide, zinc sulfide and glass, inter alia; kaolin (china clay),aluminum silicate and coprecipitates of barium sulfate and aluminumsilicate, and natural and synthetic fibrous minerals, such aswollastonite, metal, and glass fibers of various lengths. Examples ofsuitable organic fillers are carbon black, melamine, colophony,cyclopentadienyl resins, cellulose fibers, polyamide fibers,polyacrylonitrile fibers, polyurethane fibers, and polyester fibersbased on aromatic and/or aliphatic dicarboxylic acid esters, and inparticular, carbon fibers.

The inorganic and organic fillers may be used individually or asmixtures and may be introduced into the polyol composition or isocyanateside in amounts of from 0.5 to 40 percent by weight, based on the weightof components (the polyols and the isocyanate); but the content of mats,nonwovens and wovens made from natural and synthetic fibers may reachvalues of up to 80 percent by weight.

There is also provided as part of the invention a polyisocyanate-basedfoamable composition made up of an organic isocyanate component and apolyol composition component, where the C₄ -C₇ hydrocarbon blowing agentis mixed into the polyol composition ingredients and/or dispersed inboth the isocyanate component and the polyol composition ingredients.The exact amount of hydrocarbon blowing agent used in the aromaticorganic polyisocyanate and/or the polyol composition will depend uponthe desired density and solubility limits of each component.

The organic polyisocyanates include all essentially known aliphatic,cycloaliphatic, araliphatic and preferably aromatic multivalentisocyanates. Specific examples include: alkylene diisocyanates with 4 to12 carbons in the alkylene radical such as 1,12-dodecane diisocyanate,2-ethyl-1,4-tetramethylene diisocyanate, 2-methyl-1,5-pentamethylenediisocyanate, 1,4-tetramethylene diisocyanate and preferably1,6-hexamethylene diisocyanate; cycloaliphatic diisocyanates such as1,3- and 1,4-cyclohexane diisocyanate as well as any mixtures of theseisomers, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane(isophorone diisocyanate), 2,4- and 2,6-hexahydrotoluene diisocyanate aswell as the corresponding isomeric mixtures, 4,4'- 2,2'-, and2,4'-dicyclohexylmethane diisocyanate as well as the correspondingisomeric mixtures and preferably aromatic diisocyanates andpolyisocyanates such as 2,4- and 2,6-toluene diisocyanate and thecorresponding isomeric mixtures 4,4'-, 2,4'-, and 2,2'-diphenylmethanediisocyanate and the corresponding isomeric mixtures, mixtures of 4,4'-and 2,4'-diphenylmethane diisocyanates and polyphenylenepolymethylenepolyisocyanates (polymeric MDI), as well as mixtures of polymeric MDIand toluene diisocyanates. The organic di- and polyisocyanates can beused individually or in the form of mixtures.

Frequently, so-called modified multivalent isocyanates, i.e., productsobtained by the partial chemical reaction of organic diisocyanatesand/or polyisocyanates are used. Examples include diisocyanates and/orpolyisocyanates containing ester groups, urea groups, biuret groups,allophanate groups, carbodiimide groups, isocyanurate groups, and/orurethane groups. Specific examples include organic, preferably aromatic,polyisocyanates containing urethane groups and having an NCO content of33.6 to 15 weight percent, preferably 31 to 21 weight percent, based onthe total weight, e.g., with low molecular weight diols, triols,dialkylene glycols, trialkylene glycols, or polyoxyalkylene glycols witha molecular weight of up to 1500; modified 4,4'-diphenylmethanediisocyanate or 2,4- and 2,6-toluene diisocyanate, where examples of di-and polyoxyalkylene glycols that may be used individually or as mixturesinclude diethylene glycol, dipropylene glycol, polyoxyethylene glycol,polyoxypropylene glycol, polyoxyethylene glycol, polyoxypropyleneglycol, and polyoxypropylene polyoxyethylene glycols or -triols.Prepolymers containing NCO groups with an NCO content of 25 to 9 weightpercent, preferably 21 to 14 weight percent, based on the total weightand produced from the polyester polyols and/or preferably polyetherpolyols described below; 4,4'-diphenylmethane diisocyanate, mixtures of2,4'- and 4,4'-diphenylmethane diisocyanate, 2,4,- and/or 2,6-toluenediisocyanates or polymeric MDI are also suitable. Furthermore, liquidpolyisocyanates containing carbodiimide groups having an NCO content of33.6 to 15 weight percent, preferably 31 to 21 weight percent, based onthe total weight, have also proven suitable, e.g., based on 4,4'- and2,4'- and/or 2,2'-diphenylmethane diisocyanate and/or 2,4'- and/or2,6-toluene diisocyanate. The modified polyisocyanates may optionally bemixed together or mixed with unmodified organic polyisocyanates such as2,4'- and 4,4'-diphenylmethane diisocyanate, polymeric MDI, 2,4'- and/or2,6-toluene diisocyanate.

Preferably, the isocyanate used to make the closed cell rigid foams ofthe invention contain polymeric MDI, with the average functionality ofthe isocyanate component used to react with the polyol composition being2.2 or more, more preferably 2.5 or more, most preferably 2.7 or more.

The foams of the invention are closed cell, meaning that greater than80% of the cells are closed as measured for uncorrected porosity.Preferably, greater than 85%, more preferably 90% or more of the cellsare closed as measured for uncorrected porosity. The foams of theinvention are also rigid, meaning that they have a compressive strengthto tensile strength ratio of at least 1.0 and an elongation at yield ofless than 10%.

The foams of this invention are polyisocyanate based, meaning that thefoams may be considered polyurethane, polyisocyanurate, or any mixtureof the two linkages. Polyisocyanurate foams are usually made by reactingthe isocyanate component with the polyol composition component at anisocyanate index of 150 or more, preferably at an index of 250 or more,while polyurethane foams are made at isocyanate indices of 60-120, moreusually at indices of 100 to 115. The isocyanate index is defined as themolar ratio of isocyanate groups to the isocyanate reactive groupsmultiplied by 100.

The foams of the invention also exhibit numerous improvements inmechanical properties. In one embodiment of the invention, thepolyisocyanate foams employing about 8 php of the silicone containingsurfactant polymer have a 10% or less shift in thermal insulation lossover a 30 day period as measured according to ASTM C518 from a coresample of a 10% overpacked molded foam. Without the high levels ofsurfactant polymer, the thermal insulation loss at the conclusion of a30 day period is higher than 10%, such as 15-20%. The thermal insulationloss is calculated as follows: ##EQU1##

In another advantageous embodiment, the foams have reduced flammabilityas measured by the increase in weight retentions in a Butler Chimneytest. In experiments shown below, we have found that the weightretention increased by at least 3.0%, in some cases by 4.0 or 4.5%, overthe same foam using less than 8 php of the surfactant and keeping theingredients and all other amounts identical.

In a method of the invention, an organic aromatic polyisocyanate and thepolyol composition are fed through two separate lines to a high pressureimpingement mixhead. The components are intimately mixed under highpressure for less than two (2) seconds and dispensed through the mixheadonto a substrate, such as a conveyor belt, a facer, or a mold surface.The foamable mixed composition is allowed to foam and cure.

Applications for the foams made by the present invention are laminateboard for building and housing insulation, refrigeration appliancecabinets, entry way door insulation, and any other application requiringrigid polyisocyanate foams using polyester-based polyols.

The following examples illustrate the nature of the invention and do notlimit the scope of the invention as described above and in the claimsbelow. Various modification and different formulations from thosedescribed in these examples can be made within the spirit and scope ofthe invention specified herein.

Polyol A is Terate 2541, a polyester polyol derived from DMT andcommercially available from Cape Industries.

Polyol B is Weston PTP, a phosphite initiated polyol commerciallyavailable from General Electric Company.

Polyol C is Stepanpol 2502, a polyester polyol derived from phthalicanhydride containing a reacted compatibilizing agent based on a phenoliccompound, commercially available from Stepan.

L-5440 is an oxyalkylene-silicone surfactant terminated with hydrocarbongroups, commercially available from Union Carbide.

B-8462 is an oxyalkylene-silicone surfactant terminated with hydrocarbongroups commercially available from Goldschmidt.

Polycat 5 is pentamethyl-diethylene triamine, a catalyst for rigid foamapplications commercially available from Air Products.

HexCem 977 is a potassium octoate trimerization catalyst commerciallyavailable from Mooney Chemical.

Isocyanate A is a polymeric MDI having a free NCO content of 31.4, aviscosity of about 700 cps at 23° C., and having a functionality greaterthan 2.7, commercially available from BASF Corporation.

EXAMPLE 1

The polyol composition ingredients were mixed in a stainless steel,three-gallon premix tank by a drill press equipped with a Germanmixblade at 1200 rpm for about thirty (30) minutes. The stainless steelthree-gallon premix tank was positioned on a load scaled to measure theweight of the ingredients during the blending operation, and anycyclopentane gas escaping was continually replenished during theblending to keep the parts by weight of the gas constant. The premixtank was attached to a resin day tank on an Edge Sweets machine. Thecontents of the premix tank were gravity-fed to the resin day tank andkept under continuous agitation. When a shot of material was required,the polyol composition in the day tank was pumped through an in-linemixer to the mixhead, where it was impingement mixed with Iso A. Thecalibration of the machine was as stated in Table I below. Theimpingement mixed polyol composition and isocyanate were shot into #10Lilly cups for measurement of the density, and into 4"×10"×10" woodenboxes fit with cake boxes of the same dimension, which boxes were alsopacked at 10 percent beyond the theoretical needed to fill the boxvolume.

                  TABLE 1                                                         ______________________________________                                        Samples     1        2         3      4                                       ______________________________________                                        Polyol A    100      100       100    100                                     L-5440      2.0      4.0       6.0    8.0                                     HexChem 977 3.0      3.0       3.0    3.0                                     Polycat 5   0.5      0.5       0.5    0.5                                     Cyclopentane                                                                              30       30        30     30                                      Water       0.5      0.5       0.5    0.5                                     Total       136      138       140    142                                     Iso A       193.44   193.44    193.44 193.44                                  Index       300      300       300    300                                     #10 Lily Cup, pcf                                                                         1.54     1.52      1.49   1.65                                    Reactivity  3.0      3.0       3.0    3.0                                     (seconds)                                                                     Shot Time   5.3      5.0       4.5    5.6                                     Cream       30       26        25     23                                      Gel         76       78        69     69                                      Rise        46       62        48     40                                      Tack-Free                                                                     Free-Rise Box                                                                 Weight      186.6    175.2     174.4  187.1                                   Pcf         1.78     1.67      1.66   1.78                                    Shrinkage   none     face      none   none                                    Friability  surface  surface   surface                                                                              surface                                 10 Percent Packed                                                                         205.6    193.9     192.0  207.1                                   Box                                                                           Weight, grams                                                                             1.96     1.85      1.83   1.97                                    Pcf                                                                           Calibration                                                                   Resin       89.7     89.3      92.7   94.4                                    Iso         127.7    127       127.6  127.9                                   RPM Resin   633      633       653    653                                     RPM Iso     750      750       750    750                                     Pressure Resin                                                                            2000     2000      2000   2000                                    Pressure Iso                                                                              2000     2000      2000   2000                                    ______________________________________                                    

The foams packed at 10% theoretical were subjected to testing toevaluate the compressive strength according to ASTM D1621, the k-factorsaccording to ASTM C518, and the Butler Chimneys according to ASTM D3014.The results, reported in Table II below, indicate that foams made atsimilar densities having identical ingredients in identical amounts,with the exception of varying the amount of surfactant, hadsignificantly greater compressive strength, greater flammabilityresistance as measured by the greater weight retention in the ButlerChimney test, lower aged k-factors, and lower surface friability whenthe amount of surfactant was increased to 8 php. At amounts of from 2,4,and 6 php, no significant improvement in these properties was evident.At the lower levels, there existed a gradual improvement in thecompression strength and friability of the foams tested, but not in thek-factors or the flammability resistance. A significant jump incompression and friability values, and the first noticeable improvementin the k-factors and flame resistance, occurred only when the amount ofsurfactant was increased to about 8 php, suggesting that a differentchemical mechanism, besides that customarily associated with the use ofsurfactants as cell regulators, took over.

                  TABLE II                                                        ______________________________________                                        Samples      1       2         3     4                                        ______________________________________                                        Density (pcf)                                                                 overall      1.96    1.85      1.83  1.97                                     core         1.66    1.66      1.70  1.89                                     Compression @                                                                              33.2    33.4      34.6  43.4                                     yield-parr                                                                    Compression @                                                                              14.0    13.6      11.9  --                                       yield-perp                                                                    K-factor                                                                      initial      0.147   0.144     0.143 0.146                                    10 days      0.165   0.162     0.158 0.148                                    30 days      0.177   0.174     0.173 0.159                                    Butler Chimney                                                                             78.0    80.5      76.7  86.2                                     % wt. retained                                                                Porosity     97.9    98.3      95.5  96.7                                     Friability   7.4     6.7       6.5   3.4                                      ______________________________________                                    

EXAMPLE 2

In this example, further studies were conducted to evaluate theperformance of foams made with differing amounts of surfactant. The sameprocedure was used as described in Example 1 above. The amounts in partsby weight and the types of ingredients are reported in Table III below,along with the results of the foam evaluations. The foams were pouredinto molds and packed at 10% over theoretical.

                  TABLE III                                                       ______________________________________                                        Sample       1       2         3     4                                        ______________________________________                                        Polyol A     85      85        0     0                                        Polyol B     15      15        15    15                                       Polyol C     0       0         85    85                                       B-8462       2       8         2     8                                        HexCem 977   3       3         3     3                                        Polycat 5    0.3     0.3       0.3   0.3                                      Water        0.5     0.5       0.5   0.5                                      2-chloro-    7       7         7     7                                        propane                                                                       cyclopentane 23      23        23    23                                       total        135.8   141.8     135.8 141.8                                    Iso A        200     200       207   207                                      Index        300     300       300   300                                      Butler Chimney                                                                             85.4    90.11     85.66 89.08                                    av. wt. ret. %                                                                Butler Density                                                                             2.16    2.03      1.71  1.82                                     (pcf)                                                                         ______________________________________                                    

The results indicate again that foams made with 8 php of surfactant hadbetter flame retardant properties over foams made with identicalingredients except with only the conventional 2 php surfactant. Evenwhen the foams were manufactured with phosphite initiated polyols and2-chloropropane, which together assist in retarding the flammability ofpolyurethane foams, the flammability was more improved when about 8 phpof the oxyalkylene-silicone surfactant was used.

What I claim is:
 1. A method of making a polyisocyanate based closedcell rigid foam comprising reacting an organic isocyanate and a polyolcomposition in the presence of a blowing agent comprising an aliphaticor cycloaliphatic C₄ -C₇ hydrocarbon, wherein said polyol compositioncomprises:a) a polyol having polyester linkages and a number averagemolecular weight of 400 or more; and b) about 8 parts per hundred ofpolyol (php) of a silicone-containing surfactant polymer.
 2. The methodof claim 1, wherein the amount of aliphatic or cycloaliphatic C₄ -C₇hydrocarbon blowing agent is from 4 wt. % to 15 wt. % based on theweight of all foam ingredients.
 3. The method of claim 1, wherein thesurfactant contains the moiety --Si(R₂)O--, where the R groups areindependently an alkyl radical having 1 to 20 carbon atoms; analicyclic, an aryl, an alkaryl or an aralkyl having 1 to 25 carbon atomsin the alkyl group; an aliphatic ether group; or a polyester group. 4.The method of claim 3, wherein the R groups on the --Si(R₂)O-- moietyare independently alkyl radicals having from 1 to 4 carbon atoms.
 5. Themethod of claim 1, wherein the surfactant comprises anoxyalkylene-silicone polymer terminated with hydrocarbon groups.
 6. Themethod of claim 5, wherein the surfactant corresponds to the generalformula (II):

    R'.sub.3 SiO(R.sub.2 SiO).sub.y  RO(CnH.sub.2n O).sub.z SiRO!.sub.w SiR.sub.3

wherein w is an integer of at least 1, y is an integer of at least 3 andstands for the number of difunctional siloxane units; z is an integer ofat least 5 and stands for the length of a polyoxyalkylene chain; n is aninteger of 2 to 4 and stands for the number of carbon atoms in anoxyalkylene group; R' is a monovalent hydrocarbon group; and each Rgroup is independently an alkyl group or a trihydrocarbylsilyl group atan end of a siloxane group, and having a polysiloxane chain and apolyoxyalkylene chain bonded with a C--Si bond.
 7. The method of claim6, wherein the surfactant is characterized by containing 5 to 95 percentby weight of polysiloxane units, and 95 to 5 percent by weight ofpolyoxyalkylene units, and having a molecular weight of 1,000 to 16,000.8. The method of claim 6, wherein R and R' are independently C₁ -C₆alkyl radicals, and wherein the surfactant has 5 to 50 weight percentpolysiloxane units, and 95 to 50 percent by weight of polyoxyalkyleneunits.
 9. The method of claim 6, characterized by containing more than95 percent by weight of polysiloxane units and less than 5 percent byweight of polyoxyalkylene units, and having a molecular weight of 500 to10,000.
 10. The method of claim 1, wherein the silicone polymercomprises a hydroxyl functional polymer corresponding to the generalformula: ##STR13## wherein each of R are independently an alkyl radicalhaving 1 to 20 carbon atoms; an alicyclic, an aryl, an alkaryl or anaralkyl having 1 to 25 carbon atoms in the alkyl group; an aliphaticether group; or a polyester group; and wherein a secondary hydroxylfunctional group is substituted onto at least one of the R groups;eachof A are independently one or more silicon atoms containing alkyl,alicyclic, cycloalkyl, aryl, alkyloxy, alkaryl, aralkyl, or arylalkoxyhave a 1 to 25 carbon atoms in each aliphatic portion; anorganosiloxane; hydrogen; or an alkyl having 1 to 25 carbon atoms; thesum of w+x totals an integer which would correspond to an averagehydroxyl equivalent weight ranging from 200 to 4,000.
 11. The method ofclaim 1, wherein each of R are independently an alkyl having from 1 to10 carbon atoms, an alkoxy, or an ether having the formula: ##STR14##12. The method of claim 11, wherein A is hydrogen, a C₁ -C₄ alkyl, or asiloxane having the formula: ##STR15## wherein n is an integer from 1 to6, and w+x+y+z totals an integer corresponding to an average hydroxylequivalent weight of the molecule ranging from 1,250 to 3,000.
 13. Themethod of claim 1, wherein the silicone polymer comprises a hydroxylfunctional polymer represented by the formula: ##STR16## wherein R¹groups are the same or different and represent alkyl groups with 1 to 4carbon atoms, phenyl groups, or groups with the formula: ##STR17## R₂groups can have the same meaning as the R₁ groups, with the proviso thatat least one R₂ group is a hydroxyl functional C₁ -C₈ hydrocarbon or oneor more oxyalkylene groups terminated with a hydroxyl group;a has avalue of 1 to 1000; and b has a value of 0 to
 10. 14. The method ofclaim 13, wherein the silicone polymer comprises a hydroxyl functionalsilicone polymer corresponding to the formula: ##STR18## wherein each nis independently an integer ranging from 1 to 4, and w+x+y+z totals aninteger corresponding to an average hydroxyl equivalent weight of themolecule ranging from 1,250 to 3,000.
 15. The method of claim 1, whereinthe blowing agent comprises n-pentane, isopentane, cyclopentane, ormixtures thereof.
 16. The method of claim 15, further comprising water.17. The method of claim 16, wherein the polyol comprises an aromaticpolyester polyol.
 18. The method of claim 16, further comprising anorgano-phosphorous compound having at least two isocyanate reactivehydrogens.
 19. The method of claim 18, wherein the organo-phosphorouscompound comprises a trialkyl phosphite polyol.
 20. The method of claim1, comprising a polyol derived from phthalic acid, terephthalic acid,isophthalic acid, dimethyl terephthalate, polyethylene terephthalate, ormixtures thereof.
 21. The method of claim 1, wherein a) comprises anaromatic polyester polyol having an average hydroxyl number of from 30to
 550. 22. The method of claim 1, wherein the amount of all blowingagents is from 10 php to 40 php, and further comprising water in anamount 0.25 php to 1.0 php.
 23. The method of claim 1, wherein theblowing agent comprises n-pentane, isopentane, cyclopentane, or mixturesthereof, and further comprising 2-chloropropane.